| Message ID | 24039e1370ed57e8075730c0b88c505afd9e0ab7.1555085500.git.jpoimboe@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | cpu/speculation: Add 'mitigations=' cmdline option | expand |
On 4/12/19 1:39 PM, Josh Poimboeuf wrote: > Configure arm64 runtime CPU speculation bug mitigations in accordance > with the 'mitigations=' cmdline option. This affects Meltdown, Spectre > v2, and Speculative Store Bypass. > > The default behavior is unchanged. > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > --- > NOTE: This is based on top of Jeremy Linton's patches: > https://lkml.kernel.org/r/20190410231237.52506-1-jeremy.linton@arm.com > > Documentation/admin-guide/kernel-parameters.txt | 8 +++++--- > arch/arm64/kernel/cpu_errata.c | 6 +++++- > arch/arm64/kernel/cpufeature.c | 8 +++++++- > 3 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index e84a01d90e92..79bfc755defe 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2545,8 +2545,8 @@ > http://repo.or.cz/w/linux-2.6/mini2440.git > > mitigations= > - [X86,PPC,S390] Control optional mitigations for CPU > - vulnerabilities. This is a set of curated, > + [X86,PPC,S390,ARM64] Control optional mitigations for > + CPU vulnerabilities. This is a set of curated, > arch-independent options, each of which is an > aggregation of existing arch-specific options. > > @@ -2555,11 +2555,13 @@ > improves system performance, but it may also > expose users to several CPU vulnerabilities. > Equivalent to: nopti [X86,PPC] > + kpti=0 [ARM64] > nospectre_v1 [PPC] > nobp=0 [S390] > - nospectre_v2 [X86,PPC,S390] > + nospectre_v2 [X86,PPC,S390,ARM64] > spectre_v2_user=off [X86] > spec_store_bypass_disable=off [X86,PPC] > + ssbd=force-off [ARM64] > l1tf=off [X86] > > auto (default) Hi, Do we need to add "ARM64" to Documentation/admin-guide/kernel-parameters.rst?
On Fri, 12 Apr 2019, Josh Poimboeuf wrote: > Configure arm64 runtime CPU speculation bug mitigations in accordance > with the 'mitigations=' cmdline option. This affects Meltdown, Spectre > v2, and Speculative Store Bypass. > > The default behavior is unchanged. > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > --- > NOTE: This is based on top of Jeremy Linton's patches: > https://lkml.kernel.org/r/20190410231237.52506-1-jeremy.linton@arm.com So I keep that out and we have to revisit that once the ARM64 stuff hits a tree, right? I can have a branch with just the 4 first patches applied which ARM64 folks can pull in when they apply Jeremy's patches before te merge window. Thanks, tglx
On Tue, Apr 16, 2019 at 09:26:13PM +0200, Thomas Gleixner wrote: > On Fri, 12 Apr 2019, Josh Poimboeuf wrote: > > > Configure arm64 runtime CPU speculation bug mitigations in accordance > > with the 'mitigations=' cmdline option. This affects Meltdown, Spectre > > v2, and Speculative Store Bypass. > > > > The default behavior is unchanged. > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > > --- > > NOTE: This is based on top of Jeremy Linton's patches: > > https://lkml.kernel.org/r/20190410231237.52506-1-jeremy.linton@arm.com > > So I keep that out and we have to revisit that once the ARM64 stuff hits a > tree, right? I can have a branch with just the 4 first patches applied > which ARM64 folks can pull in when they apply Jeremy's patches before te > merge window. Sounds good to me (though I guess it's up to the arm64 maintainers how they want to handle the dependencies).
On Tue, Apr 16, 2019 at 09:26:13PM +0200, Thomas Gleixner wrote: > On Fri, 12 Apr 2019, Josh Poimboeuf wrote: > > > Configure arm64 runtime CPU speculation bug mitigations in accordance > > with the 'mitigations=' cmdline option. This affects Meltdown, Spectre > > v2, and Speculative Store Bypass. > > > > The default behavior is unchanged. > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > > --- > > NOTE: This is based on top of Jeremy Linton's patches: > > https://lkml.kernel.org/r/20190410231237.52506-1-jeremy.linton@arm.com > > So I keep that out and we have to revisit that once the ARM64 stuff hits a > tree, right? I can have a branch with just the 4 first patches applied > which ARM64 folks can pull in when they apply Jeremy's patches before te > merge window. Yes, that would work for us, cheers. I should get to Jeremy's latest version next week and I'm certainly planning to get them queued up for 5.2. Will
Hi Thomas, On Tue, Apr 16, 2019 at 09:26:13PM +0200, Thomas Gleixner wrote: > On Fri, 12 Apr 2019, Josh Poimboeuf wrote: > > > Configure arm64 runtime CPU speculation bug mitigations in accordance > > with the 'mitigations=' cmdline option. This affects Meltdown, Spectre > > v2, and Speculative Store Bypass. > > > > The default behavior is unchanged. > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > > --- > > NOTE: This is based on top of Jeremy Linton's patches: > > https://lkml.kernel.org/r/20190410231237.52506-1-jeremy.linton@arm.com > > So I keep that out and we have to revisit that once the ARM64 stuff hits a > tree, right? I can have a branch with just the 4 first patches applied > which ARM64 folks can pull in when they apply Jeremy's patches before te > merge window. I'm assuming that this refers to the core/speculation branch in tip: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/log/?h=core/speculation but please can you confirm that I'm good to pull that into arm64? Cheers, Will
On Wed, 24 Apr 2019, Will Deacon wrote: > Hi Thomas, > > On Tue, Apr 16, 2019 at 09:26:13PM +0200, Thomas Gleixner wrote: > > On Fri, 12 Apr 2019, Josh Poimboeuf wrote: > > > > > Configure arm64 runtime CPU speculation bug mitigations in accordance > > > with the 'mitigations=' cmdline option. This affects Meltdown, Spectre > > > v2, and Speculative Store Bypass. > > > > > > The default behavior is unchanged. > > > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > > > --- > > > NOTE: This is based on top of Jeremy Linton's patches: > > > https://lkml.kernel.org/r/20190410231237.52506-1-jeremy.linton@arm.com > > > > So I keep that out and we have to revisit that once the ARM64 stuff hits a > > tree, right? I can have a branch with just the 4 first patches applied > > which ARM64 folks can pull in when they apply Jeremy's patches before te > > merge window. > > I'm assuming that this refers to the core/speculation branch in tip: > > https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/log/?h=core/speculation > > but please can you confirm that I'm good to pull that into arm64? Yes. It's all yours :) Thanks, tglx
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index e84a01d90e92..79bfc755defe 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2545,8 +2545,8 @@ http://repo.or.cz/w/linux-2.6/mini2440.git mitigations= - [X86,PPC,S390] Control optional mitigations for CPU - vulnerabilities. This is a set of curated, + [X86,PPC,S390,ARM64] Control optional mitigations for + CPU vulnerabilities. This is a set of curated, arch-independent options, each of which is an aggregation of existing arch-specific options. @@ -2555,11 +2555,13 @@ improves system performance, but it may also expose users to several CPU vulnerabilities. Equivalent to: nopti [X86,PPC] + kpti=0 [ARM64] nospectre_v1 [PPC] nobp=0 [S390] - nospectre_v2 [X86,PPC,S390] + nospectre_v2 [X86,PPC,S390,ARM64] spectre_v2_user=off [X86] spec_store_bypass_disable=off [X86,PPC] + ssbd=force-off [ARM64] l1tf=off [X86] auto (default) diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index a1f3188c7be0..65bcd7f0cca1 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -19,6 +19,7 @@ #include <linux/arm-smccc.h> #include <linux/psci.h> #include <linux/types.h> +#include <linux/cpu.h> #include <asm/cpu.h> #include <asm/cputype.h> #include <asm/cpufeature.h> @@ -405,6 +406,9 @@ static bool has_ssbd_mitigation(const struct arm64_cpu_capabilities *entry, this_cpu_safe = true; } + if (cpu_mitigations_off()) + ssbd_state = ARM64_SSBD_FORCE_DISABLE; + if (psci_ops.smccc_version == SMCCC_VERSION_1_0) { ssbd_state = ARM64_SSBD_UNKNOWN; if (!this_cpu_safe) @@ -599,7 +603,7 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope) } /* forced off */ - if (__nospectre_v2) { + if (__nospectre_v2 || cpu_mitigations_off()) { pr_info_once("spectrev2 mitigation disabled by command line option\n"); __hardenbp_enab = false; return false; diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 6b7e1556460a..d826b17f7820 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -25,6 +25,7 @@ #include <linux/stop_machine.h> #include <linux/types.h> #include <linux/mm.h> +#include <linux/cpu.h> #include <asm/cpu.h> #include <asm/cpufeature.h> #include <asm/cpu_ops.h> @@ -966,7 +967,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, MIDR_ALL_VERSIONS(MIDR_HISI_TSV110), { /* sentinel */ } }; - char const *str = "command line option"; + char const *str = "kpti command line option"; bool meltdown_safe; meltdown_safe = is_midr_in_range_list(read_cpuid_id(), kpti_safe_list); @@ -988,6 +989,11 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, __kpti_forced = -1; } + if (cpu_mitigations_off() && !__kpti_forced) { + str = "mitigations=off"; + __kpti_forced = -1; + } + /* Useful for KASLR robustness */ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset() > 0) { if (!__kpti_forced) {
Configure arm64 runtime CPU speculation bug mitigations in accordance with the 'mitigations=' cmdline option. This affects Meltdown, Spectre v2, and Speculative Store Bypass. The default behavior is unchanged. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- NOTE: This is based on top of Jeremy Linton's patches: https://lkml.kernel.org/r/20190410231237.52506-1-jeremy.linton@arm.com Documentation/admin-guide/kernel-parameters.txt | 8 +++++--- arch/arm64/kernel/cpu_errata.c | 6 +++++- arch/arm64/kernel/cpufeature.c | 8 +++++++- 3 files changed, 17 insertions(+), 5 deletions(-)